1. Field of the Invention
The present invention relates to a formulation of a solid synthetic fuel, or synfuel, and in particular to the chemical change agent (CCA) useful for such synfuel. More particularly, this invention relates to CCA's using tall oil pitch emulsions and fatty acid emulsions.
2. Description of the Prior Art
Solid synfuels can be produced from coal through a chemical interaction between feedstock coal and a CCA. Synthetic fuels have been recognized as a desirable alternative fuel source. Section 29 of the Internal Revenue Code recognizes qualified fuels, including solid synthetic fuel produced from coal, by giving tax credits for producing fuel from a non-conventional source. These synthetic fuels must exhibit “significant chemical change” when compared to the feedstocks.
Emulsions using tall oil pitch have been used as a binder, for production of synthetic fuel and also for the asphalt industry. An example of using tall oil pitch as a carboneous binder can be found in U.S. Pat. No. 5,188,658 issued to Aune et al. In Aune, tall oil pitch was used as a carboneous binder in an agglomerating said zinc containing material. However, previous emulsions were ineffective to create the degree of chemical change required. Other difficulties with known tall oil pitch emulsions excessively high viscosity, and material handling difficulties. An example of such a tall oil pitch emulsion can be found in U.S. Pat. No. 4,437,896 issued to Partanen. The Partanen emulsion was prepared from blends of tall oil and/or tall oil pitch and naturally occurring or man made gilsonite.
U.S. Pat. No. 6,077,340 to Doyle (hereinafter “Doyle patent”) teaches a chemically-stabilized emulsion of tall oil in an aqueous emulsifier solution. The aqueous emulsifier solution comprises water, acids, and emulsifiers. The pH of the emulsion is controlled between 3 and 7 to prevent saponification and neutralization of the naturally occurring acids in the tall oil. To help stabilize the emulsion, the tall oil and water comprise a majority by weight of the emulsion. This emulsion is used for soil treatment, for reclamation of asphalt and remediation of heavy metal contaminated soil. While a tall oil-in-water emulsion is disclosed, this emulsion is used as a binder typically for soil stabilization and not as a CCA.
In addition to teaching that the emulsion is for use in the reclamation of asphalt, not in the creation of synfuel, the Doyle patent teaches the use of an emulsion that has a pH below the 6.5 to 7.0 range. This pH range would allow microbial growth in an emulsion containing fatty acids, particularly in the 5.0 to 7.0 pH range. Raising the pH of the CCA to the 7 to 10 range controls the formation of anaerobic bacteria. Increasing storage temperature and provisions for storage tank agitation have also proven effective to reduce microbial growth.
While Doyle discloses an emulsion of tall oil in water, this emulsion is applied only to the disparate soil remediation industry, and not the synfuel industry. The Doyle emulsion, which contains primarily tall oil, would not be an effective CCA for synfuel. Finally, saponification is undesirable in Doyle but is useful in one embodiment of the current invention as the addition of caustic not only adjusts pH, but also creates soap in the oil.
Examples of known binders for use as a chemical change agent include the CCA taught in U.S. Pat. No. 5,178,640 to Girardi. The Girardi patent discloses a method for preparing a synthetic fuel, or synthetic components for fuels, using a polycarboxylic acid mixture for the oxidation of coal. While this patent teaches a CCA that avoids the use of asphalt with its deleterious environmental consequences, the Girardi patent requires an oxidation process, which is much more expensive than the process required in the present invention, which only requires mixing and pressing.
Other types of pitches have been utilized in prior art. One such example is found in U.S. Pat. No. 4,822,425 issued to Burch (hereinafter “Burch patent”) that discloses an aggregate-stabilizing emulsion of pine tar pitch, rosin, an emulsifying agent and water for use in road construction. Again, the use of this emulsion is very different from the CCA of the current invention to create synfuel. While rosins are the residue of distillation products of resins and the oleoresins contain essential oils, the composition of rosin varies greatly from the triglycerides of the current invention.
It is, therefore, an object of this invention to provide synthetic fuel producers with a CCA that is more readily available, most reactive when combined with coal, more economical, and more environmentally friendly. The incorporation of fatty acids within the CCA have resulted in an improved CCA for synfuel applications.
It is a related object of this invention to provide an asphalt emulsion that produces a product that flows when crushed and that has incendiary properties similar to coal, preventing premature combustion. It is another object to produce a synfuel that minimizes safety risks when stored or processed and produce an emulsion with improved characteristics for handling and application. Further objects of this invention are to minimize the total cost of producing a qualified synthetic fuel with given performance characteristics and increase the diversity of available supply for solid phase of CCA formulation. Other objectives include providing a CCA capable of producing enhanced chemical change when compared to current tall oil pitch emulsions and producing a CCA with lower viscosity for a given chemical change capacity. It is yet a further object to create an environmentally-friendly CCA.